Anti-government activists say air strikes have killed at least 12 people at a market and other targets in the north-western Syrian city of Idlib.

The Britain-based Syrian Observatory for Human Rights, which relies on a network of activists on the ground, says at least 12 people died when several air strikes struck the insurgent-held city on Sunday.

It said the number of casualties is likely to rise.

The Local Coordination Committees, another anti-government monitoring group, says the strikes killed 13 and wounded 29, with most casualties occurring in a vegetable market.

Idlib is controlled by a coalition of Syrian rebel groups that includes al Qaida's local branch, the Nusra Front.